1. Field of the Invention
The invention relates to a directly heated oxide cathode, especially for velocity-modulated tubes in pulse operation.
2. Description of the Prior Art
Directly heated oxide cathodes are known, for instance from German DE-AS No. 21 60 145 (U.S. Pat. No. 3,775,166) and German DE-AS No. 29 04 653 (U.S. Pat. No. 4,215,180). Such oxide cathodes consist essentially of a cathode body (base metal plate) of a high-resistivity alloy and an electron-emitting layer. The base metal plate is designed in the shape of a yoke. The oxide layer is applied to the outside of the flat part of the base metal plate. At the ends of the base metal plate facing away therefrom, are provided leads for the d-c voltage souce.